Commitments and Contingencies MEC Acquisition (Details) - MEC Holdings LLC [Member] - Unregulated Operation [Member] $ in Millions	12 Months Ended
Dec. 31, 2019 USD ($) MW
Public Utilities, General Disclosures [Line Items]
Property, Plant, and Equipment, Additional Disclosures \| MW	760
Property, Plant and Equipment, Additions \| $	$ 650

Amount of acquisition of long-lived, physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration